US6091190AExpiredUtility

Field emission device

83
Assignee: MOTOROLA INCPriority: Jul 28, 1997Filed: Jul 28, 1997Granted: Jul 18, 2000
Est. expiryJul 28, 2017(expired)· nominal 20-yr term from priority
Inventors:Babu ChalamalaSung P. PackCharles A. Rowell
H01J 1/3042H01J 29/04H01J 2201/30426H01J 1/30
83
PatentIndex Score
45
Cited by
29
References
19
Claims

Abstract

An electron emitter (121, 221, 321, 421) includes an electron emitter structure (118) having a passivation layer (120, 220, 320, 420) formed thereon. The passivation layer (120, 220, 320, 420) is made from an oxide selected from a group consisting of the oxides of Ba, Ca, Sr, In, Sc, Ti, Ir, Co, Sr, Y, Zr, Ru, Pd, Sn, Lu, Hf, Re, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Th, and combinations thereof. In the preferred embodiment, the electron emitter structure (118) is made from molybdenum, and the passivation layer (120, 220, 320, 420) is made from an emission-enhancing oxide having a work function that is less than the work function of the molybdenum.

Claims

exact text as granted — not AI-modified
We claim: 
     
       1. An electron emitter comprising: an electron emitter structure having a surface, wherein the electron emitter structure comprises a material having a first work function; and   a passivation layer disposed on the surface of the electron emitter structure, wherein the passivation layer comprises an oxide, and wherein the oxide has a second work function, the second work function of the oxide being less than the first work function of the material comprising the electron emitter structure.   
     
     
       2. The electron emitter of claim 1, wherein the electron emitter has a surface, and wherein the oxide defines the surface of the electron emitter. 
     
     
       3. The electron emitter of claim 1, wherein the oxide is selected from a group consisting of the oxides of Ba, Ca, Sr, In, Sc, Ti, Ir, Co, Y, Zr, Ru, Pd, Sn, Lu, Hf, Re, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Th, and combinations thereof. 
     
     
       4. The electron emitter of claim 3, wherein the oxide is selected from a group consisting of BaO, Ba 3  WO 6 , CaO, SrO, In 2  O 3 , Sc 2  O 3 , TiO, IrO 2 , Y 2  O 3 , ZrO 2 , RuO 2 , PdO, SnO 2 , Lu 2  O 3 , HfO 2 , ReO 3 , La 2  O 3 , Ce 2  O 3 , Pr 2  O 3 , Nd 2  O 3 , Pm 2  O 3 , Sm 2  O 3 , Eu 2  O 3 , Gd 2  O 3 , Tb 2  O 3 , Dy 2  O 3 , Ho 2  O 3 , Er 2  O 3 , Tm 2  O 3 , Yb 2  O 3 , ThO 2 , In 2  O 3  :SnO 2 , BaTiO 3 , BaCuO x , xBaO.HfO 2 , Bi 2  Sr 2  CaCu 2  O x , YBa 2  Cu 3  O 7-x , SrRuO 3 , (Ba,Sr)O, (La,Sr)CoO 3 , and (BaO) n .(Ta 2  O 3 ) m , where x, n, and m are integers. 
     
     
       5. The electron emitter of claim 1, wherein the passivation layer consists essentially of an oxide. 
     
     
       6. The electron emitter of claim 5, wherein the oxide is selected from a group consisting of the oxides of Ba, Ca, Sr, In, Sc, Ti, Ir, Co, Y, Zr, Ru, Pd, Sn, Lu, Hf, Re, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Th, and combinations thereof. 
     
     
       7. The electron emitter of claim 6, wherein the oxide is selected from a group consisting of BaO, Ba 3  WO 6 , CaO, SrO, In 2  O 3 , Sc 2  O 3 , TiO, IrO 2 , Y 2  O 3 , ZrO 2 , RuO 2 , PdO, SnO 2 , Lu 2  O 3 , HfO 2 , ReO 3 , La 2  O 3 , Ce 2  O 3 , Pr 2  O 3 , Nd 2  O 3 , Pm 2  O 3 , Sm 2  O 3 , Eu 2  O 3 , Gd 2  O 3 , Tb 2  O 3 , Dy 2  O 3 , Ho 2  O 3 , Er 2  O 3 , Tm 2  O 3 , Yb 2  O 3 , ThO 2 , In 2  O 3  :SnO 2 , BaTiO 3 , BaCuO x , xBaO.HfO 2 , Bi 2  Sr 2  CaCu 2  O x , YBa 2  Cu 3  O 7-x , SrRuO 3 , (Ba,Sr)O, (La,Sr)CoO 3 , and (BaO) n .(Ta 2  O 3  ) m , where x, n, and m are integers. 
     
     
       8. The electron emitter of claim 1, wherein the electron emitter structure comprises molybdenum. 
     
     
       9. The electron emitter of claim 1, wherein the electron emitter structure is comprised of a material, and wherein the passivation layer has a greater resistance to oxidation than the material. 
     
     
       10. A field emission device comprising: a substrate having a surface;   a cathode disposed on the surface of the substrate;   a dielectric layer disposed on the cathode and defining an emitter well;   an electron emitter structure disposed within the emitter well and having a surface, wherein the electron emitter structure comprises a material having a first work function;   a passivation layer disposed on the surface of the electron emitter structure to define an electron emitter, wherein the passivation layer comprises an oxide, and wherein the oxide has a second work function, the second work function of the oxide being less than the first work function of the material comprising the electron emitter structure; and   an anode opposing the electron emitter.   
     
     
       11. The field emission device of claim 10, further including a gate electrode disposed on the dielectric layer. 
     
     
       12. The field emission device of claim 10, wherein the electron emitter has a surface, and wherein the oxide defines the surface of the electron emitter. 
     
     
       13. The field emission device of claim 10, wherein the oxide is selected from a group consisting of the oxides of Ba, Ca, Sr, In, Sc, Ti, Ir, Co, Y, Zr, Ru, Pd, Sn, Lu, Hf, Re, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Th, and combinations thereof. 
     
     
       14. The field emission device of claim 13, wherein the oxide is selected from a group consisting of BaO, Ba 3  WO 6 , CaO, SrO, In 2  O 3 , Sc 2  O 3 , TiO, IrO 2 , Y 2  O 3 , ZrO 2 , RuO 2 , PdO, SnO 2 , Lu 2  O 3 , HfO 2 , ReO 3 , La 2  O 3 , Ce 2  O 3 , Pr 2  O 3 , Nd 2  O 3 , Pm 2  O 3 , Sm 2  O 3 , Eu 2  O 3 , Gd 2  O 3 , Tb 2  O 3 , Dy 2  O 3 , Ho 2  O 3 , Er 2  O 3 , Tm 2  O 3 , Yb 2  O 3 , ThO 2 , In 2  O 3  :SnO 2 , BaTiO 3 , BaCuO x , xBaO.HfO 2 , Bi 2  Sr 2  CaCu 2  O x , YBa 2  Cu 3  O 7-x , SrRuO 3 , (Ba,Sr)O, (La,Sr)CoO 3 , and (BaO) n .(Ta 2  O 3 ) m , where x, n, and m are integers. 
     
     
       15. The field emission device (100, 200, 300, 400) of claim 10, wherein the passivation layer (120, 220, 320, 420) consists essentially of an oxide. 
     
     
       16. The field emission device of claim 15, wherein the oxide is selected from a group consisting of the oxides of Ba, Ca, Sr, In, Sc, Ti, Ir, Co, Y, Zr, Ru, Pd, Sn, Lu, Hf, Re, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Th, and combinations thereof. 
     
     
       17. The field emission device of claim 16, wherein the oxide is selected from a group consisting of BaO, Ba 3  WO 6 , CaO, SrO, In 2  O 3 , Sc 2  O 3 , TiO, IrO 2 , Y 2  O 3 , ZrO 2 , RuO 2 , PdO, SnO 2 , Lu 2  O 3 , HfO 2 , ReO 3 , La 2  O 3 , Ce 2  O 3 , Pr 2  O 3 , Nd 2  O 3 , Pm 2  O 3 , Sm 2  O 3 , Eu 2  O 3 , Gd 2  O 3 , Tb 2  O 3 , Dy 2  O 3 , Ho 2  O 3 , Er 2  O 3 , Tm 2  O 3 , Yb 2  O 3 , ThO 2 , In 2  O 3  :SnO 2 , BaTiO 3 , BaCuO x , xBaO.HfO 2 , Bi 2  Sr 2  CaCu 2  O x , YBa 2  Cu 3  O 7-x , SrRuO 3 , (Ba,Sr)O, (La,Sr)CoO 3 , and (BaO) n .(Ta 2  O 3 ) m , where x, n, and m are integers. 
     
     
       18. The field emission device (100, 200, 300, 400) of claim 10, wherein the electron emitter structure (118) comprises molybdenum. 
     
     
       19. The field emission device (100, 200, 300, 400) of claim 10, wherein the electron emitter structure (118) is comprised of a material, and wherein the passivation layer (120, 220, 320, 420) has a greater resistance to oxidation than the material.

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